Simple Tools to Figure Out My Yard Slope

Items you may have on hand can help you calculate slope.

Knowing the slope of your yard is important when you want to install a variety of water-sensitive devices, such as drains or sprinkler heads, and it is also just handy to know. If you don’t want to pay a lot of money for surveying information that includes your yard's slope, then consider using some simple tools to get the job done instead.

Slope Determination

The basic formula for calculating slope is rise over run. If you imagine a right triangle, rise is its vertical leg that extends upward from the triangle's 90-degree angle. Run is the horizontal leg extending along the bottom of the triangle. The slope is the third leg of the triangle, stretching between the other two legs. Dividing rise by run gives you a basic equation for slope. Multiplying the resulting number by 100 gives you the percent of the slope.

Pencil and Paper

If you have professional surveying information for your property, either conducted by someone you hired or by a previous homeowner, then the easiest way to determine your yard’s slope is simply to use that information and a pencil and paper. Elevation information for the height at the top and bottom of the slope is needed, as are property measurements. Subtract the height at the bottom of the slope from the height at the slope's top, which give you the slope's rise. Divide that number by the total horizontal length the slope covers from its top to its bottom. That length is the slope's run.

Stakes and String

Using stakes and string is the best calculation method for a gentle slope. Pound one stake into the top of the hill and one stake into the hill's bottom. The top end of the stake at the bottom of the hill has to equal the height of the top of the hill. Tie a string to the hill's top stake at ground level, and then extend the string until it reaches the hill's bottom stake. Holding the string against the bottom stake, move it up and down until a carpenter's level placed on top of the string is balanced, with the level's bubble right in the middle of the display marks for levelness. Tie the string off at that point, and measure the length of the string -- the slope's run -- and the height from the bottom of the stake to the string knot -- the slope's rise.

Short Stick

If your yard has a small slope, such as the kind that is surrounded on all sides by flat ground, you can easily measure it by simply using a stick. The stick needs to be equal in length to the distance between your eye and the end of your hand. Face the slope, and hold out the stick so it points upward vertically on your arm while you simultaneously hold that arm stretched out straight. Match up the bottom end of the stick to the bottom of the hill and the top of the stick to the top of the hill. Getting on your knees or belly may be necessary to do that task. Move backward and/or forward until stick height matches hill height. Choose a parallel path along the slope, walking from the point where the stick height matches to the midpoint of the slope: The distance equals the slope's height, or rise. The distance from the bottom to the top of the slope is the run.